Qubit circuit state change control system

• US 10,063,228 B2
• Filed: 02/19/2016
• Issued: 08/28/2018
• Est. Priority Date: 02/19/2015
• Status: Active Grant

• Current Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno, Technische Universiteit Delft
• Original Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Inventors: Deurloo, Duije, Dicarlo, Leonardo
• Primary Examiner(s): Zweizig, Jeffrey
• Application Number:
  US15/552,066
• Publication Number:
  US 20180013426A1
• Time in Patent Office: 921 Days
• CPC Class Codes: G06N 10/00 Quantum computing, i.e. information processing based on quantum-mechanical phenomena
• CPC Class Codes: H03K 17/693 Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors logic circuits H03K19/00; code converters H03M5/00, H03M7/00
• CPC Class Codes: H03K 17/92 by the use, as active elements, of superconductive devices
• CPC Class Codes: H03K 19/1952 with electro-magnetic coupling of the control current
• CPC Class Codes: H03K 3/38 by the use, as active elements, of superconductive devices

Abstract

A qubit system is provided wherein successive sets of M RF pulses are generated simultaneously, for application to qubit circuits in a plurality of N groups of M qubit circuits. M switching multiplexer circuits are used, each to pass a respective one of the M RF pulses in the set to a selected one of a plurality of N M to one RF combiners in a multiplexing mode. Combined RF pulses at M different RF frequencies are transmitted from each of the N combiners to a transmission structure for a respective one of the groups. Individual ones of the combined RF pulses are coupled from the transmission structure for the group to respective ones of the qubit circuits of the groups via respective frequency selective filters. In a broadcast mode the M switching multiplexer circuits are used to transmit the simultaneous pulses to all of RF combiners.

Claims

1. A qubit circuit system comprising:

a plurality of N groups of M qubit circuits, wherein N and M are a first and second integers greater than one;

a plurality of N RF transmission structures, each corresponding to a respective one of the groups of qubit circuits;

a plurality of N groups of M frequency selective filters, each group of frequency selective filters being coupled between a respective one of the N RF transmission structures and its corresponding group of qubit circuits, the M frequency selective filters in each group of frequency selective filters being configured for selectively passing RF signals at respective different pass frequencies to respective ones of the qubit circuits in the corresponding group;

a plurality of M time division multiplexing systems, each time division multiplexing system comprising an RF pulse generator and a controllable one-to-N multiplexer with an input coupled to an output of the RF pulse generator, the RF pulse generators of each of the time division multiplexing systems being operable to produce RF pulses containing undulations at a respective one of the pass frequencies of the M frequency selective filters in the groups of frequency selective filters;

a plurality of N RF combiners, each having M inputs coupled to outputs of the one-to-N multiplexers of each of the M time division multiplexing systems, each RF combiner having an output coupled to a respective one of the RF transmission structures; and

a control circuit having first control outputs coupled to modulation inputs of the RF pulse generators and second control outputs coupled to control inputs of the controllable one-to-N multiplexers, the control circuit being configured to control successive transmission of simultaneous RF pulses from the RF pulse generators, and to control the controllable one-to-N multiplexers to pass individual ones of the RF pulses to selectable ones of the outputs of the one-to-N multiplexers in a multiplexing mode.

2. A system according to claim 1, wherein the control circuit is configured to control the one-to-N multiplexer of at least one of the time division multiplexing systems selectably alternatively in the multiplexing mode and a broadcast mode, wherein the one-to-N multiplexer passes an RF pulse from the RF pulse generator of at the least one of the time division multiplexing systems to all outputs of the one-to-N multiplexer of the at least one of the time division multiplexing system.

3. A system according to claim 1, wherein the control circuit is configured to control the one-to-N multiplexer of at least one of the time division multiplexing systems selectably alternatively in the multiplexing mode and a multicast mode, wherein the one-to-N multiplexer passes an RF pulse from the RF pulse generator of at the least one of the time division multiplexing systems to outputs of a subset containing a plurality of the one-to-N multiplexers of the at least one of the time division multiplexing systems.

4. A system according to claim 1, comprising amplitude adapter circuits in RF signal paths from the time division multiplexing systems to the inputs of the RF combiner, the control circuit comprising third control outputs coupled to control inputs of amplitude adapter circuits for individually controlling amplitude adaptation by individual ones of the amplitude adapter circuits.

5. A system according to claim 1, wherein the RF pulse generator of each of the time division multiplexing systems comprises:

a local RF oscillator and

a first and second mixer with inputs coupled to the local RF oscillator,

the time division multiplexing system comprising;

a further controllable one-to-N multiplexer, inputs of the controllable one-to-N multiplexer and the further controllable one-to-N multiplexer being coupled to outputs of the first and second mixer respectively,

controllable amplitude adapter circuits in RF signal paths from outputs of the controllable one-to-N multiplexer and/or in RF signal paths from outputs of the further controllable one-to-N multiplexer to the inputs of the RF combiners,

the control circuit comprising third control outputs coupled to control inputs of at least part of the amplitude adapter circuits for individually controlling adaptation of an amplitude ratio between RF pulse amplitudes of RF pulses passed by the controllable one-to-N multiplexer and further controllable one-to-N multiplexer.

6. A system according to claim 4, comprising controllable phase adapters in series with the amplitude adapters, the control circuit comprising fourth control outputs coupled to control inputs of at least part of the amplitude adapter circuits, for individually controlling adaptation of a phase difference between RF pulses passed by the controllable one-to-N multiplexer and further controllable one-to-N multiplexer.

7. A method of controlling qubit circuit state changes, of qubit circuits in a plurality of N groups of M qubit circuits, wherein N and M are a first and second integers greater than one, the method comprising:

generating successive sets of M RF pulses simultaneously, each set containing M RF pulses at different RF frequencies;

in a multiplexing mode, using M switching multiplexer circuits each to pass a respective one of the M RF pulses in the set to a selected one of a plurality of N M-to-one RF combiners;

transmitting combined RF pulses at M different RF frequencies from each of the N combiner to a transmission structure for a respective one of the groups; and

coupling individual ones of the combined RF pulses from the transmission structure for the group to respective ones of the qubit circuits of the groups via respective frequency selective filters.

8. A method of controlling qubit circuit state changes according to claim 7, switching to a broadcast mode for part of the sets and switching the M multiplexer circuits each to pass a respective one of the M RF pulses in the set to all of the plurality of N M to one RF combiners.

9. A method of controlling qubit circuit state changes according to claim 7, switching to a multicast mode for part of the sets and switching the M multiplexer circuits each to pass a respective one of the M RF pulses in the set to a multicast subset of the plurality of N M-to-one RF combiners, the multicast subset comprising a plurality of the RF combiners.

10. A method according to claim 7, comprising controlling amplitude adaptation of the RE pulses between the M switching multiplexer circuit and the RF combiners.

11. A method according to claim 7, comprising

generating successive sets of M collections of RF pulses simultaneously, each collection comprising a first and second different RF pulse at the same frequency simultaneously, different collections in the set containing different RF frequencies;

in the multiplexing mode, using 2*M switching multiplexer circuits each to pass a respective first and second RF pulses in the set to a corresponding selected ones of the plurality of N M-to-one RF combiners; and

transmitting combined RF pulses at M different RF frequencies containing the first and second RE pulse signals to the transmission structure for a respective one of the groups.

12. A method according to claim 10, comprising controlling adaptation of a ratio of amplitudes of the first and second RF pulses between the M switching multiplexer circuits and the RF combiners.